Homebrew PCBs

Hi

I am designing and building a pwm motor controller.

I am desigining it to run a DC motor with a maximum current of 8 amps and 12 Volts DC supply.

I am using surface mount components and using home etched PCB's.

I am now at the stage of designing the PCB layout. I have been investigating the current caryying capacity of the copper clad board and the track widths needed.

I have found an equation that calculates the minimum track width but this depends on the maximum temperature rise that I allow.

What is a suitable temperature rise?


I will most liley be using FR4 board, with a copper thickness of (1oz) 34uM. 
For example if I allow a rise in temperature pf 20 degress C the width is 3.4mm or 136.7 mil
10 degress the track width is 5.22mm or 208 mil.

I will be using mosfet and diodes in this circuit all of wich will have heat sinks. The connection from the board to the motor will be via a cable connected to the pcb by terminal blocks.

I presume it is best practice to have the track between the mosfet and the terminal block as short as possible? Is there any good practice measures I should be aware of here, can the fets and diodes be too close to the terminals or can i come straight from the mosfet pins to the pcb terminals then leaving the board?


Thank you.